The candidate, Marius Sudol, is committed to basic cancer research in academia. He is a graduate of the Rockefeller University and his appreciation of the stimulating and intense atmosphere at the University influenced his decision to continue his career here. The award would certainly enhance his progress toward the status of independent investigator. Some of the projects proposed by him require long-term strategies which award would make possible. Under new administration, the Rockefeller University is planning to reorganize its current academic structure with special emphasis on an independent junior faculty. These changes should be beneficial to candidates such as Marius Sudol. The major aim of his research is to define cellular and molecular processes in which proto-oncogenes of the src-family are involved. Among the various projects which he proposes, two deserve mention here because of their originality and potential for generating important results. These are: 1. identification of proteins that interact with the regulatory regions of the yes and src oncogene products by screening cDNA expression libraries with anti-idiotypic antibodies; and 2. isolation of substrate proteins that are phosphorylated on tyrosine in vivo and that associate with the cellular-src kinase in A431 cells treated with calcium ionophore. The immediate goals of his research are the identification of molecules that associate with tyrosine kinases and the characterization of processes by which these molecules communicate with each other. Even though the emphasis of the experiments proposed is on the molecular mechanisms of proto-oncogene action, it is anticipated that the results will have broad implications for our understanding of processes that control cellular growth and differentiation in general. Moreover, knowledge of the molecular mechanisms of proto-oncogene action could also provide the basis for an understanding of how transforming genes subvert normal growth control, and could point towards potential therapies for controlling malignant diseases in humans.